the fit is generally very tight between the right and left levers via the D shaped hole. If you didn't get a right side safety lever with the TS safety, I'd opt to fit the TS Safety lever to the Shadow 2 right side lever so if you wanted to revert you don't change the original safety fitment.
Are you sure they don't fit, I'd check outside the gun if they fit together or not. Sometimes getting it all lined up in the gun is a pain.
For the interference with the slide release, I'd just remove the front edge of the safety to get it to clear properly. You can cold blue it but it doesn't last long. I'd consider having it refinished once the reshaping is complete and you like the ergo's.
Cheers,
Toby